ELG3175 Introduction to
Communication Systems
Frequency Response,
Energy and Power
Frequency Response of Linear Time
Invariant Systems
An LTI system is described by its impulse response,
h(t).
For an input x(t), the output is y(t) which is given by
y (t

ELG3175 Introduction to
Communication Systems
Conventional AM
Disadvantages of DSB-SC
The receiver must generate a replica of the carrier in
order to demodulate a DSB-SC signal.
Any phase and/or frequency error will result in a
distorted estimate of the

ELG3175 Introduction to
Communication Systems
Frequency-Domain
Representation:
Fourier Series and
Fourier Transform
Generalized Fourier Series
We are given a set of functions cfw_n(t)n=1,2,N which
are mutually orthogonal on the interval to t to + T.
t o

ELG3175
Differential Pulse Code Modulation
and Delta Modulation
Differential PCM
In PCM, the data rate is Nfs, where fs = sampling rate and N =
number of bits per sample.
Consecutive samples are encoded independently.
L = 2N is the number of quantizati

ELG3175 Introduction to
Communication Systems
VSB and Introduction
to Angle Modulation
Motivation
For wideband information signals, SSB is difficult to
implement.
For frequency discrimination, the filter must have a
sharp cutoff near the frequency fc so

ELG3175 Introduction to
Communication Systems
Fourier transform,
Parsevals theoren,
Autocorrelation and
Spectral Densities
Fourier Transform of a Periodic
Signal
A periodic signal can be expressed as a complex
exponential Fourier series.
If x(t) is a pe

Lecture 11
Differential PCM
Samples of a bandlimited signal are correlated -> previous
sample gives information about the next one. Example: if
previous samples are small, the next one will be small with
high probability.
This can be used to improve PCM

Lecture 10
Pulse-Amplitude Modulation
Baseband modulation
PAM -> conversion of an analog signal to a pulse-type signal in
which the pulse amplitude carriers the analog information.
This is the 1st step in converting an analog signal (waveform) to
a dig

Lecture 7
Single Sideband (SSB) AM
Why SSB-AM? Spectral efficiency is of great importance.
Conventional & DSB-SC occupy twice the message
bandwidth.
All the information is contained in either half the other is
redundant.
Spectral efficiency can be gre

Lecture 3
Review of Fourier Transform
Fourier series works for periodic signals only. Whats
about aperiodic signals? This is very large & important
class of signals
Aperiodic signal can be considered as periodic for
T
Fourier series changes to Fourier

ELG3175 Introduction to
Communication Systems
Quadrature and
Single Sideband AM
Quadrature Amplitude Modulation
(QAM)
Spectral efficiency refers to the amount of information
that we can transmit per unit bandwidth
DSB-SC transmita a signal with bandwidt

Recent Documents

ELG3175 Introduction to
Communication Systems
Introduction to
Amplitude
Modulation: DSB-SC
Introduction to modulation
A message signal, m(t), is to be transmitted.
Let us assume that this is a baseband signal with
bandwidth Bm.
In other words, M(f) = 0

ELG3175 Introduction to
Communication Systems
Introduction and
Review of LTI
Systems and
Convolution
Introduction
Communications in EE refers to the transmission of
information from one point to another using electrical
systems.
Organization of a commun